• Erez Shitrit's avatar
    IB/mlx4: Fix WQE LSO segment calculation · 90615370
    Erez Shitrit authored
    commit ca9b590caa17bcbbea119594992666e96cde9c2f upstream.
    
    The current code decreases from the mss size (which is the gso_size
    from the kernel skb) the size of the packet headers.
    
    It shouldn't do that because the mss that comes from the stack
    (e.g IPoIB) includes only the tcp payload without the headers.
    
    The result is indication to the HW that each packet that the HW sends
    is smaller than what it could be, and too many packets will be sent
    for big messages.
    
    An easy way to demonstrate one more aspect of the problem is by
    configuring the ipoib mtu to be less than 2*hlen (2*56) and then
    run app sending big TCP messages. This will tell the HW to send packets
    with giant (negative value which under unsigned arithmetics becomes
    a huge positive one) length and the QP moves to SQE state.
    
    Fixes: b832be1e ('IB/mlx4: Add IPoIB LSO support')
    Reported-by: 's avatarMatthew Finlay <matt@mellanox.com>
    Signed-off-by: 's avatarErez Shitrit <erezsh@mellanox.com>
    Signed-off-by: 's avatarOr Gerlitz <ogerlitz@mellanox.com>
    Signed-off-by: 's avatarDoug Ledford <dledford@redhat.com>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    90615370
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